One of the first five paired, biramous, ventral limbs of the pleotelson. In unmodified form, it consists of a basal segment, the protopod, and two distal rami, the endopod and the exopod. The rami may be biarticulate. Female Asellota lack the first pleopods. In male Asellota, the first pleopods are present only as uniramous structures (fused into a single elongate plate in the superfamily Janiroidea). The rami of the male second pleopod are modified as copulatory structures. Pleopods III-V have very thin cuticle and function as gills (branchiae).